The Philips SH30/50 replacement shaving heads are designed to restore your shaver to its original performance. This silver-colored set includes three heads compatible with the Philips Series 1000 (S1xxx), Series 3000 (S3xxx), and the Star Wars SW3700 model. Because blades naturally wear down after cutting approximately 9 million hairs, these heads should be replaced every two years to ensure a clean and efficient shave. They provide a simple way for users of these specific series to maintain their device's cutting power without needing a completely new shaver.